Nitrous Oxide: mostly from agriculture (the application
of fertilizers, feedlots) and auto emissions.

Fluorinated Gases: hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride are synthetic chemicals used in industry (these are alternatives to CFCs, etc. that have been banned).

Water Vapor is another very important greenhouse gas.

3. The most likely cause
of global warming/climate change is increases in greenhouse gas concentrations in the atmosphere
largely due to human pollution, especially fossil fuel burning but also deforestation,
livestock, rice paddies, pipeline leaks, and landfills.